A related-art disk motor includes an output shaft, an approximately disk-shaped coil disk fixed to the output shaft and printed with a coil pattern, a commutator disk having a commutator pattern connected to the coil pattern, a magnet disposed to face the coil pattern and a brush for applying electric current to the commutator pattern (see, Japanese Patent No. 3636700).
A rotational number of the disk motor is determined in accordance with a voltage supplied from the brush, an electric current of the disk motor, a coil pattern of the coil disk, a magnetic flux of the magnet and a number of the brushes (number of poles). When the voltage supplied from the brush and the electric current of the disk motor are constant, it is possible to set the rotational number of the disk motor at a desired rotational number by changing the coil pattern of the coil disk, the magnetic flux of the magnet and the number of the brushes.
JP-A-2004-80996 is not directed to a disk motor but to a technology for improving a cooling and radiating performance of a stator coil in a commutator motor by increasing the cooling and radiating surface area of the stator coil.